Engine rollback – ‘the crew(s) were partly to blame’.
With hindsight this view is bit harsh. The icing phenomenon was previously unknown and only after the statistics from events was it associated with very large Cbs. More recently Boeing and Airbus have encountered problems.
There were some human aspects, particularly after the initial warnings not to fly anywhere near Cbs, but also there were more general circumstances. Many of the incident aircraft were relatively light, thus cruised at a (relatively) higher altitude; crews believed that no return on radar was the same as no threat due to mismanagement/misunderstanding of WXR – corner cutting near Cbs, and some of the engine air-bleed tolerances were at minimum - maintenance.
In at least one event a crew ‘induced’ depressurisation (four engines shut down – not in Oz), presented an interesting dilemma between descending relatively fast (for lack of O2/pressure), pausing at FL200 to obtain a relight, or to reduce altitude loss to maximise the much need overwater glide range. Again, with hindsight, a compromise at FL200 provided a balance between risks and needs; at least the engines relit.
In many aircraft, crews over reacting to a depressurisation warning; pilots are taught the depressurisation drill in association with an emergency descent, thus they become automatically sequential. Whereas in reality after donning the O2 masks, there is time to check the actual cabin pressure and cabin rate, and possibly some fault diagnosis.
The more experienced 146 Captains would look at the overhead panel and check the outflow valves, which under manual control had a sluggish response and lacked feed back of the selection except for air pressure on the ears. Many pilots did not have opportunity to gain this knowledge from annual airtests (now discontinued), and the simulator was ineffective.
Depressurisation; a quick response required for O2 masks, no rush to descend … check … then act accordingly.